1. Field of the Invention
The present invention relates generally to methods and apparatus for handling and storing pipes and other elongated tubular members during well drilling, preparation, and maintenance. More specifically, the present invention relates to systems for holding, containing, storing, and restraining elongated tubular members in a controlled manner within a racking board, or fingerboard, or another structure.
2. Background of the Technology
Oil and gas well drilling systems employ numerous types of piping, referred to generally as “tubulars.” Tubulars include, for example, drill pipes, casings, collars, and other elongate tubular members that are connectable end-to-end. Long “strings” of joined tubulars, or drill strings, are typically used to drill a wellbore and to prevent collapse of the wellbore after drilling. Segments of drill strings, such as individual sections of drill pipe or multiple sections of drill pipe that have been threaded together, are typically stored vertically on the drilling rig in a structure commonly referred to as a racking board. Racking boards (also known as a finger board) include a plurality of elongated support members or “fingers,” the space between each pair of fingers capable of receiving multiple drill string segments. It is the upper end of a segment that is restrained by the racking board. The lower end of the segment rests on or near the drill floor.
In land rigs, the drill string segments are typically manually placed in the land rig racking board by an individual known as a derrick man, or sometimes by a remotely operated mechanical arm. As the segments are being added to or removed from the drill string, the derrick man maneuvers the top end of a segment into and out of a lifting device called an elevator. The drill string segments can vary in diameter depending on the type of well being drilled and the stage of the drill plan. While the segments are being stored in the racking board, their ends are typically tied back with rope so as to resist wind forces, vibration, and rig lean. Rigs which utilize a mechanical arm to rack the segments also require a means of securing them in the racking board. On larger offshore drilling units, with computerized control systems, this is typically accomplished with an individually controlled mechanical latches, one latch for restraining each drill string segment. This method and the control system to operate it are usually cost prohibitive in the land rig market so it is necessary to restrain the segments in the racking board without individually controlled latches. As mentioned, hand-tied ropes are commonly employed on land rigs, but this method is cumbersome. In addition, even where the rig includes an automated mechanical arm for use in the racking operation, there is a requirement on land rig applications to be able to return to manual racking quickly when the mechanical racking arm is out of service. Accordingly, a means for the timely disabling of any systems that would prevent manual racking is required. Conventional handling systems for drill string segments are described in U.S. Pat. Publication No. 20080164064 and U.S. Pat. Nos. 7,736,119 and 7,083,007, incorporated herein by reference in their entirety.
Accordingly, there remains a need for improved methods and apparatus for restraining tubular members within a racking board on a drilling rig while the tubulars are stored for subsequent use in forming the drill string.